Daryl or Michonne
Because in the Sneak peak (in the end) you can see a "blanket" that would fit to both of them.
But you can also see that Rick has blood on his right side of the face that could mean that it was someone from his right with that blanket...
And on this Picture you can see that literally everyone i like the most is on the right...
And you can see that he got no blood on his face in the Pircute

And in this Picture he got some blood on his right side of his face...
This Picture is from the Sneak Peak video